The present application is directed generally to an evaporator arrangement. Specifically, the present application is directed to a liquid collection and drainage system to remove liquid refrigerant from vapor refrigerant in an evaporator.
In a refrigeration circuit, refrigerant vapor passes from the evaporator to the compressor. If the refrigerant isn't completely changed to vapor in the evaporator, some liquid refrigerant may be passed on to the compressor as liquid carryover. This liquid carryover can affect both the performance and the life of the compressor.
For example, in a flooded evaporator that has liquid refrigerant introduced in the lower part of the evaporator shell to exchange heat with a fluid passing through a tube bank, liquid droplets may be entrained in the refrigerant vapor flow leaving the evaporator after exchanging heat with the fluid within the tube bank. One approach to solving this problem is to provide a liquid/vapor separator, either internally or externally of the evaporator. While these separators are effective, they add substantial expense to the system.
Another approach to removing liquid refrigerant from the refrigerant vapor in the evaporator has been to provide sufficient vertical space between the top of the tube bank and the suction nozzle at the top of the evaporator shell such that any liquid droplets will be caused to flow downwardly by the force of gravity before they reach the suction nozzle. This approach requires the use of a larger shell, which is costly because of the added materials and space that it requires.
Yet another approach for removing liquid refrigerant has been to provide a so-called “mist eliminator” in the form of a wire mesh, between the top of the tube bank and the compressor suction. Such an eliminator tends to interrupt the flow of the liquid droplets, allowing them to collect on the eliminator and to eventually fall by force of gravity. This approach is somewhat effective in controlling liquid carryover and while it requires less space then the approach described hereinabove, it does require some additional space for the eliminator and also involves additional cost. In addition, the eliminator is recognized as being a passive system in the sense that it simply turns back the droplets, which will tend to be entrained in the flow of refrigerant vapor as before. Furthermore, the eliminator causes pressure drop of the vapor flow resulting in degradation of the performance of the chiller.
Other approaches for removing liquid refrigerant include providing a baffle above the tube banks for interrupting and collecting the upward flow of liquid refrigerant droplets that would otherwise tend to flow to the compressor along with the refrigerant vapor. Heat may be added to the baffle to cause an evaporation of the liquid droplets such that the resulting vapor passes to the compressor. However, this approach does not offer an effective drainage of the liquid collected by the baffle.
Intended advantages of the methods and/or systems satisfy one or more of the needs or provide other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the claims, regardless of whether they accomplish one or more of the aforementioned needs.